1. Field of the Invention
The present invention relates to a semiconductor memory device, and particularly, the present invention relates to a device suitable for applying to a dynamic type random access memory.
2. Description of the Related Art
A dynamic type random access memory (DRAM) is applied to various electronic products, such as an image data memory and a personal computer.
In recent years, such electronic products including DRAMs have been more and more required to operate at high speeds. Also, in order to realize such high speed operation, the DRAMs themselves are requested to operate at higher speed. A read operation which reads out data form memory cells of the DRAM is particularly required to be shortened.
In the case where the high speed operation of the DRAM is realized, it is desirable to avoid complicating the process to manufacture such a DRAM. Because as processes of the DRAM become complex, the cost of the DRAM becomes higher. It is also desirable to minimize the number of transistors used. This is because as the number of transistors is minimized, the size of the DRAM is reduced.